1. Field of the Invention
This invention relates to height adjusting devices, and more particularly to a set of adjustable legs for desks and other furniture.
2. Brief Description of the Prior Art
Sitting at a desk or work table for prolonged periods of time is a common cause of neck, shoulder and back pain. It is common practice for desk users to employ adjustable chairs and stools which offer limited adjustments in height relative to the desk. The adjustment of the chair or stool is largely a matter of compromise and often unsatisfactory due to the wide variations in height and physical characteristics of the user.
Desks having height adjustment means are known in the art. There are several patents which disclose various height adjusting mechanisms which offer limited height adjustment of desks and other furniture.
Brown, U.S. Pat. No. 2,544,822 discloses an adjustable base for desks. The base is provided with an elongated base member containing a vertically sliding bar-like foot piece having upwardly inclined slots which carry a cam plate. An adjusting screw co-acts with a nut on the cam plate whereby rotation of the screw moves the cam plate longitudinally to raise and lower the base relative to the foot piece.
Fox, U.S. Pat. No. 2,545,949 discloses a desk elevator comprising a pair of elongated island type support members. The support members consist of a spring connected base member and top member having opposed inwardly inclined surfaces at each end. A threaded shaft is turned by a screw driver to move a pair of opposed wedge members inwardly on the inclined faces thereby separating the base and top members to raise and lower the desk.
Blumenberg, U.S. Pat. No. 1,762,046 discloses an adjustable car seat wherein a conventional hand crank jack operates a set of pivotally mounted levers to raise and lower the seat.
Stevens, U.S. Pat. No. 3,606,255 discloses a scissors jack which is raised and lowered by rotation of a pair of parallel threaded rods. A chain is connected to sprockets mounted on each rod whereby force transmitted to one of the rods is transmitted to the other. The parallel drive means reduces torsional forces and frictional loads to permit level raising and lowering even though the jack may be supporting an unbalanced load.
Adamson, Jr., U.S. Pat. No. 3,976,281 discloses a variable height work surface which is adjustable from a low profile to a desired level by utilizing double acting scissor legs controlled by a screw mechanism.
The prior art in general, and none of these patents in particular, disclose a set of adjustable legs for raising and lowering desks and other furniture comprising outer tubular members attachable to the desk or other furniture and inner tubular members slidably and non-rotatably received within the outer members and adapted for vertical movement relative thereto, a threaded shaft having a sprocket on its upper portion and rotatably mounted within the members for moving the inner member relative to the outer member, and a chain interconnecting the sprockets of each of the shafts for simultaneous rotational movement to move the inner member along the shaft and thereby raise and lower the desk.